The influence of divalent cations and substrate concentration on the incorporation of myo-inositol into phospholipids of isolated bovine oligodendrocytes.
The incorporation of myo-inositol into phosphatidylinositol by two routes (CTP-independent and CTP-independent) has been investigated in homogenates prepared from isolated bovine oligodendrocyte perikarya. The CTP-dependent route has the higher maximum velocity of inositol incorporation and can utilise either Mn2+ or Mg2+ as a divalent ion cofactor. This route of inositol incorporation is also strongly inhibited by Ca2+ ions at concentrations less than 1 mM. The primary site of the inhibitory action appears to be the enzyme CDP-diglyceride inositol phosphatidyl transferase (EC 2.7.8.11) though synthesis of CDP-diacylglycerol is also inhibited by endogenous Ca2+ present in the oligodendrocyte homogenate. In contrast, CTP-independent inositol incorporation into phosphatidylinositol is only stimulated by Mn2+ (Zn2+,Cu2+, Mg2+, Ca2+ and Co2+ are ineffective) and is not inhibited by Ca2+, at least up to a concentration of 1 mM.
D000818:Animals; D002118:Calcium / Q000502:physiology; D002413:Cations, Divalent; D002417:Cattle; D003567:Cytidine Diphosphate Diglycerides / Q000378:metabolism; D003570:Cytidine Triphosphate / Q000502:physiology; D004533:Egtazic Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D007294:Inositol / Q000378:metabolism*; D008274:Magnesium / Q000502:physiology; D008345:Manganese / Q000502:physiology; D009457:Neuroglia / Q000378:metabolism*; D009836:Oligodendroglia / Q000378:metabolism*; D009994:Osmolar Concentration; D010716:Phosphatidylinositols / Q000378:metabolism*
D002413:Cations, Divalent; D003567:Cytidine Diphosphate Diglycerides; D010716:Phosphatidylinositols; D008345:Manganese; D007294:Inositol; D004533:Egtazic Acid; D003570:Cytidine Triphosphate; D008274:Magnesium; D002118:Calcium